JP2007103750A - Circuit module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit module capable of forming interconnections from integrated circuit elements to terminal electrodes without increasing their area at the time of mounting the integrated circuit elements having a number of input-output terminals. <P>SOLUTION: The circuit module A comprises a first module substrate 1A, an integrated circuit element 4 arranged on the first module substrate, and a second module substrate 1B with a cavity 11 for housing the element 4 formed on the lower surface and junction fixed on the substrate 1A. The element 4 has a plurality of input-output terminals on the lower surface, a plurality of land electrodes 3 are formed in the region for arranging the integrated circuit elements of the substrate 1A, and the input-output terminals of the element 4 are face-down mounted to the electrode 3. A plurality of terminal electrodes 9 electrically connected to the electrode 3 are formed on the lower surface of the substrate 1A. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a circuit module on which an integrated circuit element having a large number of input / output terminals such as a semiconductor element is mounted.

2. Description of the Related Art Conventionally, circuit modules used in wireless devices such as mobile phones and automobile phones and other various communication devices are known in which a large-scale integrated circuit element such as a baseband signal processing IC is mounted on a module substrate. ing. Large-scale integrated circuit elements generally have tens to hundreds of input / output terminals. Among these input / output terminals, other components inside the module and wiring provided on or in the module substrate are used. Some are connected directly to terminal electrodes formed on the bottom surface of the module, and some are connected to circuits and elements on a motherboard on which the module is mounted. In particular, in the case of a circuit in which advanced control is performed, the number of input / output terminals is increased, and it is necessary to perform several tens to several hundreds of wirings from the integrated circuit element to the terminal electrodes of the module.

As a module for mounting an integrated circuit, as shown in FIG. 6, an integrated circuit element 41 is mounted on the upper surface of a module substrate 40, and input / output terminals of the integrated circuit element 41 and land electrodes 42 on the upper surface of the module substrate 40 are connected. In addition to being connected by wire bonding 43, the land electrode 42 and the terminal electrode 44 formed on the bottom surface of the module substrate 40 are connected via an internal wiring 45 such as a via hole, and the integrated circuit element 41 is protected as necessary. A structure in which a cover and a resin mold are provided on the upper surface of the module substrate 40 is known. When the circuit scale of the module is large, it can be dealt with by making the module substrate 40 a multilayer substrate.

However, in this structure, the wiring connecting the input / output terminals of the integrated circuit element 40 and the terminal electrode 46 of the module occupies a certain volume from the top surface to the bottom surface of the module substrate 40, so the number of wirings is large. When the number increases, the volume of the module substrate 40 occupied by the wiring becomes large, which causes a problem that miniaturization is hindered.
Therefore, in the case of a circuit module on which the integrated circuit element 41 having a large number of input / output terminals is mounted, it is desirable for miniaturization to arrange the integrated circuit element 41 as close to the bottom surface of the module substrate 40 as possible.

As a circuit module incorporating an integrated circuit element, a structure shown in Patent Document 1 is known. In this circuit module, as shown in FIG. 7, a cavity 51 is provided on the bottom surface of a module substrate 50 having a multilayer structure, an integrated circuit element 52 is face-up mounted on the upper bottom surface of the cavity 51, and a resin 53 is molded in the cavity 51. ing. The integrated circuit element 52 having a low mechanical strength can be protected by housing the integrated circuit element 52 in the cavity 51 and molding it with the resin 53.

In Patent Document 1, since the integrated circuit element 52 is disposed near the bottom surface of the entire module, a certain size reduction is possible. However, since the integrated circuit element 52 is mounted face up, Wire bonding 54 is required. When the number of input / output terminals of the integrated circuit element 52 increases, it is necessary to provide a large number of lands for the wire bonding 54 in the cavity 51, and the area of the cavity 51 must be increased, and the area efficiency of the module is reduced. To do. Further, after being connected from the integrated circuit element 52 to the land of the module substrate 50, it is necessary to perform wiring further to the terminal electrode 55 provided on the bottom surface of the module substrate 50. However, the wiring is formed below the cavity 51 portion. Since this is not possible, the wiring to the terminal electrode 55 must be spread around the cavity 51. Therefore, when the integrated circuit element 52 has multiple terminals, there is a problem that the area of the module increases by the space of the wiring.

If the mounting of the integrated circuit element is changed to the face-down mounting, the wire bonding is not required, so that the cavity area can be reduced. However, the space for wiring to the terminal electrode cannot be reduced. That is, in the method of providing the cavity 51 on the bottom surface of the module substrate 50 and mounting the integrated circuit element 52 on the top and bottom surfaces of the cavity 51, there is a problem that the area of the wiring from the integrated circuit element 52 to the terminal electrode 55 of the module increases. There is.

As another module structure, in Patent Document 2, as shown in FIG. 8, a recess 61 is formed on the upper surface of the first circuit board 60, and an integrated circuit element 62 is mounted on the bottom surface of the recess 61. A structure in which the second circuit board 63 is fixed so as to cover 61 is disclosed. In the case of this structure, the integrated circuit element 62 is mounted face-up on the upper surface of the concave portion 61 of the first circuit board 60, and a heat radiating portion 64 is formed on the bottom surface of the first circuit board 60. A through hole 65 for radiating heat generated by the integrated circuit element 61 is formed in the element mounting portion 60.

In the circuit module having this structure, since the input / output terminals of the integrated circuit element 62 are connected to the wiring provided on the first circuit board 60, the first circuit board 60 is independent of the size of the second circuit board 63. Wiring to the terminal electrode 66 provided on the bottom surface of the substrate can be provided. However, since the integrated circuit element 62 is mounted face up, the mounting area of the integrated circuit element 62 including the land for wire bonding is still required to be large. Further, Patent Document 2 has a theme of dissipating the heat of the integrated circuit element 62 through the circuit board 60 thereunder, and face-down mounting is not originally considered. Therefore, the element mounting portion of the first circuit board 60 cannot be effectively used as a wiring space.
JP 2002-299775 A JP 2003-1000093 A1

Accordingly, an object of the present invention is to provide a circuit module capable of forming wiring from an integrated circuit element to a terminal electrode without increasing the area when an integrated circuit element having a large number of input / output terminals is mounted. is there.

In order to achieve the above object, a circuit module according to the present invention includes a first module board, a circuit element disposed on the first module board, and a space for accommodating the circuit element on a lower surface. And a second module substrate bonded and fixed on the first module substrate. The circuit element is an integrated circuit element having a plurality of input / output terminals on the lower surface. A plurality of land electrodes are formed in a region of the module substrate where the circuit board is disposed, and input / output terminals of the circuit elements are mounted face-down on the land electrodes. A plurality of terminal electrodes electrically connected to the land electrodes are formed.

The circuit module of the present invention has a circuit element mounted face-down on a first module board, and a second module board having a space for accommodating the circuit element on the lower surface is bonded and fixed on the first module board. is there. In this case, no land for wire bonding is required, so that the substantial mounting area of the integrated circuit element can be reduced. The substantial size of the space provided under the second module substrate may be slightly larger than the size of the integrated circuit element. Since most of the land electrodes face-down mounted to the input / output terminals of the integrated circuit element and the wiring connecting the land electrodes and the terminal electrodes of the module can be formed directly under the integrated circuit element, the above-mentioned space is provided for the wiring space. It doesn't have to be wide. Also, the wiring between the upper second module substrate and the lower first module substrate does not include the wiring from the input / output terminals of the integrated circuit elements to the terminal electrodes of the module. Can be small.

The present invention is effective when most of the input / output terminals of the circuit element are connected to the terminal electrodes.
Most of the input / output terminals of the circuit element may be connected to the internal circuit of the module, but in that case, the number of wires from the input / output terminal of the circuit element to the terminal electrode of the module is small, and the wiring space is also small. I'm sorry. However, when most of the input / output terminals of the circuit elements are connected to the terminal electrodes, a large wiring space is required, and the circuit area of the conventional circuit module increases. On the other hand, in the present invention, the area under the mounting portion of the circuit element can be used as a wiring space. Therefore, even when most of the input / output terminals of the circuit element are connected to the terminal electrode, the area of the module can be reduced.

A first connection portion is formed on the upper surface of the first module substrate and outside the region where the circuit element is disposed, and the first connection portion is formed on the lower surface of the second module substrate and excluding the space. Two connecting portions are formed, and the first connecting portion and the second connecting portion can be connected to each other.
When connecting the first module substrate and the second module substrate to each other, a first connection portion is formed on the outer periphery of the element mounting portion of the first module substrate, and on the first connection portion, If the second connection portion formed in the peripheral portion of the space provided under the second module substrate is connected, both module substrates can be reliably connected.

The occupied area of the circuit element may be at least half of the occupied area of the second module substrate.
In the case where the circuit element is a small element less than 1/2 of the area occupied by the second module substrate, a relatively large wiring area can be secured in a portion not overlapping with the circuit element in the space under the second module substrate. When the circuit element is ½ or more of the area occupied by the second module substrate, the space in the space below the second module substrate that does not overlap with the circuit element is reduced, and the wiring space is also reduced. . In such a case, the structure of the present invention that can use the circuit element mounting portion as a wiring space is effective.

A circuit component may be mounted on the upper surface of the space forming region of the second module substrate, and a resin layer for embedding the circuit component may be formed on the upper surface of the second module substrate. .
Circuit modules are required to be further miniaturized and densified, and by mounting additional circuit components on the top surface of the second module substrate, especially the top surface of the space forming area, improvement in area efficiency and densification are realized. it can. In that case, by covering the circuit component with the resin layer, the insulation between the circuit component and the outside can be secured, and the circuit component can be protected.

The occupied area of the first module substrate is formed larger than the occupied area of the second module substrate, and the upper surface of the first module substrate is in a region where the second module substrate is not fixed. A structure in which circuit parts are mounted may be employed.
In this case, by mounting another circuit component on the upper surface of the first module board without overlapping the upper surface of the second module board, the height of the entire module can be increased by balancing the height. Multifunctional circuit modules can be realized without

The space may be a cavity provided on the bottom surface of the second module substrate, or by mounting the second module substrate on the first module substrate via a columnar member, It may be a space formed.
In the former case, a sealed space can be formed by bonding the second module substrate on the first module substrate, and the circuit element can be accommodated in the sealed space.
In the latter case, since a gap can be formed between the columnar members, it is possible to inject an underfill resin into the lower surface of the circuit element through the gap after mounting the second module substrate.

As described above, according to the present invention, since the integrated circuit element is mounted face-down on the first module substrate, the element mounting portion of the first module substrate can be effectively used as a wiring space. Even when an integrated circuit element having an output terminal is mounted, wiring from the integrated circuit element to the terminal electrode can be formed without increasing the area of the module substrate, and the circuit module can be miniaturized.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 shows a first embodiment of a circuit module according to the present invention.
The circuit module A includes a module substrate 1 in which a first module substrate 1A and a second module substrate 1B made of an insulating substrate such as resin or ceramics are stacked.

The first module substrate 1A is composed of a multilayer substrate. A plurality of land electrodes 3 are formed on the upper surface of the first module substrate 1A, and an integrated circuit element 4 having a large number of input / output terminals 4a is mounted face-down through bumps 5 thereon. Yes. Note that flip-chip mounting may be performed without using the bumps 5. Further, an underfill resin may be provided as appropriate in the gap between the integrated circuit element 4 and the first module substrate 1A. Inside the first module substrate 1A, a conductor wiring 7 connected to the land electrode 3 via the via hole 6 is provided, and the conductor wiring 7 is formed on the bottom surface of the first module substrate 1A via the via hole 8. The terminal electrode 9 is connected. In this example, the terminal electrode 9 is composed of an LGA terminal. Most of the land electrode 3 is connected to the terminal electrode 9, and most of the wiring 6, 7, 8 is arranged in a region immediately below the integrated circuit element 4, that is, in a region of the element mounting portion. A plurality of connection electrodes 10 are formed on the outer peripheral portion of the upper surface of the first module substrate 1A. These connection electrodes 10 are connected to the terminal electrodes 9 or the conductor wirings 7 through via holes (not shown), or the land electrodes 3. Connected with.

The second module substrate 1B is also made of a multilayer substrate, and a cavity 11 for forming a space for surrounding and housing the integrated circuit element 4 in a non-contact manner is formed at the center of the bottom surface. Conductor wiring 12 is formed on the upper surface of the second module substrate 1B, and a plurality of circuit components 13 are mounted on the conductor wiring 12. The circuit component 13 may be an active component such as a transistor or a passive component such as a capacitor, resistor, or inductor. The resin layer 14 is formed on the upper surface of the second module substrate 1B, and the circuit component 13 and the conductor wiring 12 are embedded in the resin layer 14. A connection electrode 16 connected to the connection electrode 10 of the first module substrate 1A is connected to the lower surface of the peripheral wall portion 15 excluding the cavity 11 of the second module substrate 1B, that is, the joint surface with the upper surface of the first module substrate 1A. Is formed. The connection electrode 16 is connected to the conductor wiring 18 formed inside the second module substrate 1 </ b> B through the via hole 17, and the conductor wiring 18 is further connected to the conductor wiring 12 through the via hole 19.

In this embodiment, the occupied area of the first module substrate 1A and the second module substrate 1B is equal, and the occupied area of the integrated circuit element 4 is 1/2 or more of the occupied area of the first module substrate 1A and the second module substrate 1B. Is set to Since the integrated circuit element 4 is an element having a large number (several tens to several hundreds) of input / output terminals 4a, a large wiring space from the input / output terminals 4a to the terminal electrodes 9 is required. Since it is mounted face-down on one module substrate 1A, the area directly under the integrated circuit element 4, that is, the element mounting portion of the first module substrate 1A can be used as a wiring space, and the wiring space extends widely outside the element mounting portion. Can be prevented. Therefore, the area outside the element mounting portion can be used as a connection portion between the first module substrate 1A and the second module substrate 1B. Since the number of wires from the second module substrate 1B to the first module substrate 1A is smaller than the number of wires from the integrated circuit element 4 to the terminal electrode 9, a small wiring space is sufficient, and the thickness of the peripheral wall portion 15 is reduced. it can.

(Second Embodiment)
2 and 3 show a second embodiment of a circuit module according to the present invention.
In the circuit module B of this embodiment, the occupied area of the first module substrate 1A is larger than that of the second module substrate 1B, and a relatively tall space such as a coil or a filter is formed in a blank area on the first module substrate 1A. The electronic component 20 is mounted. The first module substrate 1A is, for example, a printed wiring board having six wiring layers, and the integrated circuit element 4 is face-down mounted on the upper surface thereof. As shown in FIG. 3, which is a partially enlarged sectional view, the second module substrate 1B has a cavity 11 that forms a space for accommodating the integrated circuit element 4 on the bottom surface, and a low-profile circuit component 21 is mounted on the top surface. The structure is covered with a mold resin layer 22 from above. The circuit component 21 is formed, for example, by stacking a plurality of thin integrated circuit elements and wire bonding wiring. A shield case 23 is disposed on the first module substrate 1A and forms an electromagnetic shield for the entire circuit module B. However, the shield case 23 can be omitted.

The first and second module substrates 1A and 1B may be organic substrates or ceramic substrates, but it is particularly preferable to use an LTCC (low temperature fired ceramic) substrate as the second module substrate 1B. The LTCC substrate is characterized in that the unit thickness of the insulating layer in the case of multilayer wiring can be reduced compared to the organic substrate, and the land diameter of the via hole and the interval between adjacent vias can be reduced. Above, it can be made smaller and lower than the organic substrate. Therefore, the area of the entire module can be reduced. Moreover, when the component 21 on the second module substrate 1B dominates the height of the entire module, the height of the module can be reduced.

In this embodiment, the integrated circuit element 4 having a large number of terminals effectively uses the lower part of the integrated circuit element 4 as a wiring area and is wired in the first module substrate 1A, so that the wiring extending around the element 4 can be reduced. Furthermore, since another circuit component 21 can be disposed on the second module substrate 1B having the cavity 11, the area of the entire module can be reduced.
The relatively low components 20 are arranged on the first module substrate 1A without overlapping, and the low components 21 are stacked to balance the height, so that the optimal low is achieved even in the area and height constraints. The back and downsizing can be achieved.

(Third embodiment)
4 and 5 show a third embodiment of a circuit module according to the present invention.
As shown in FIG. 5 as a partially enlarged sectional view, the circuit module C of this embodiment is the same as the circuit module B of the second embodiment except for the structure of the second module substrate 1B.
The second module substrate 1B is formed in a flat plate shape, and a plurality of columnar member conductor columns 30 are provided around the lower surface of the second module substrate 1B, and mechanically and electrically with the first module substrate 1A via these conductor columns 30. It is connected. That is, the conductor pillar 30 has a role of wiring between the first module substrate 1A and the second module substrate 1B. Note that an insulating columnar member may be used for a portion that does not require a wiring function. A gap is formed between the first module substrate 1A and the second module substrate 1B depending on the height of the conductor pillar 30, and the integrated circuit element 4 face-down mounted on the first module substrate 1A is disposed in the gap. Has been. In other words, a portion of the gap surrounded by the conductor pillar 30 is a space for accommodating the integrated circuit element 4.

An underfill resin may be provided between the integrated circuit element 4 and the first module substrate 1A. When the underfill resin protrudes around the element 4, the second module substrate 1B is mounted on the first module substrate 1A. In this embodiment, since there is a gap between the conductor pillars 30, it is possible to inject the underfill resin after mounting the second module substrate 1B. Therefore, the protrusion of the underfill resin does not interfere with the connection of the second module substrate 1B.

In each of the above embodiments, the first module substrate 1A and the second module substrate 1B are both configured as multilayer substrates, but either one or both substrates may be configured as a single layer substrate.
When either the first module substrate 1A or the second module substrate 1B is formed of a multilayer substrate, electronic components such as capacitors and resistors can be integrally formed or embedded in the substrate.
The circuit components 13 and 21 are mounted on the upper surface of the second module substrate 1B and the periphery thereof is covered with the resin layers 14 and 22. However, instead of the resin layers 14 and 22, a shield case may be covered.
The number of integrated circuit elements 4 mounted facedown on the first module substrate 1A is not limited to one, and a plurality of integrated circuit elements 4 may be provided.

It is sectional drawing of 1st Embodiment of the circuit module concerning this invention. It is a side view of 2nd Embodiment of the circuit module concerning this invention. FIG. 3 is an enlarged cross-sectional view of a second module substrate portion of the circuit module shown in FIG. 2. It is a side view of 3rd Embodiment of the circuit module concerning this invention. It is an expanded sectional view of the 2nd module board | substrate part of the circuit module shown in FIG. It is sectional drawing of an example of the conventional circuit module. It is sectional drawing of the circuit module shown by patent document 1. FIG. It is sectional drawing of the circuit module shown by patent document 2. FIG.

Explanation of symbols

A, B, C Circuit module 1A First module substrate 1B Second module substrate 3 Land electrode 4 Integrated circuit element 4a Input / output terminal 5 Bump 6, 7, 8 Wiring 9 Terminal electrode 11 Cavity 13 Circuit component 14 Resin layer

Claims (8)

A first module substrate, a circuit element disposed on the first module substrate, and a space for accommodating the circuit element is formed on the lower surface, and has a predetermined circuit, and on the first module substrate. A second module substrate bonded and fixed,
The circuit element is an integrated circuit element having a plurality of input / output terminals on the lower surface,
A plurality of land electrodes are formed in a region where the circuit board is disposed on the first module board,
The input / output terminals of the circuit element are mounted face down on the land electrode,
A circuit module, wherein a plurality of terminal electrodes electrically connected to the land electrode are formed on a lower surface of the first module substrate. 2. The circuit module according to claim 1, wherein most of the input / output terminals of the circuit element are connected to the terminal electrodes. A first connection portion is formed on the upper surface of the first module substrate and outside the region where the circuit element is disposed,
A second connection portion is formed on a lower surface of the second module substrate, excluding the space,
The circuit module according to claim 1, wherein the first connection portion and the second connection portion are connected to each other. 4. The circuit module according to claim 1, wherein an occupied area of the circuit element is ½ or more of an occupied area of the second module substrate. 5. The circuit component is mounted on the upper surface of the space forming region of the second module substrate, and a resin layer for embedding the circuit component is formed on the upper surface of the second module substrate. Item 5. The circuit module according to any one of Items 1 to 4. The occupied area of the first module substrate is formed larger than the occupied area of the second module substrate, and the upper surface of the first module substrate is in a region where the second module substrate is not fixed. 6. The circuit module according to claim 1, wherein circuit components are mounted. 7. The circuit module according to claim 1, wherein the space is a cavity provided on the bottom surface of the second module substrate. 7. The space according to claim 1, wherein the space is a space formed between both module substrates by mounting the second module substrate on the first module substrate via a columnar member. The circuit module described in 1.

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